¹Research Scholar , Civil Engg Department Sardar Vallabhbhai National Institute of Technology,Surat Gujrat,395.007(India)

²Prof &Head , Civil Engg Department,  Sardar Vallabhbhai National Institute of Technology,Surat Gujrat-395.007 (india)

The friction factor of an open channel flow is generally affected by the characteristics of the fluid, flow, geometry of the channel and the characteristics of the channel boundary. So, here the attempt has been made to compute the friction factor following the different methods and an approach based on the field data of 15 years of Tapi River for monsoon season and studies the variation of friction factor with Shear velocity Reynolds number. The mathematical model to predict the friction factor for the Tapi River at Savkheda Gauging station has been developed by using the average value of the friction factor obtained by various methods based on various approaches and the multiple regression analysis. The multiple regression analysis has been carried out by using the non-linear curve fitter of the origin 7.5 software. The mathematical model has been developed relating the Shear velocity Reynolds number with the friction factor.